112 lines
2.5 KiB
Go
112 lines
2.5 KiB
Go
package dns
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import (
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"bytes"
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"context"
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"crypto/tls"
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"io"
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"net"
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"net/http"
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"github.com/Dreamacro/clash/component/dialer"
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"github.com/Dreamacro/clash/component/resolver"
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D "github.com/miekg/dns"
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)
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const (
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// dotMimeType is the DoH mimetype that should be used.
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dotMimeType = "application/dns-message"
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)
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type dohClient struct {
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url string
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transport *http.Transport
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}
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func (dc *dohClient) Exchange(m *D.Msg) (msg *D.Msg, err error) {
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return dc.ExchangeContext(context.Background(), m)
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}
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func (dc *dohClient) ExchangeContext(ctx context.Context, m *D.Msg) (msg *D.Msg, err error) {
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// https://datatracker.ietf.org/doc/html/rfc8484#section-4.1
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// In order to maximize cache friendliness, SHOULD use a DNS ID of 0 in every DNS request.
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newM := *m
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newM.Id = 0
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req, err := dc.newRequest(&newM)
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if err != nil {
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return nil, err
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}
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req = req.WithContext(ctx)
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msg, err = dc.doRequest(req)
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if err == nil {
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msg.Id = m.Id
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}
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return
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}
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// newRequest returns a new DoH request given a dns.Msg.
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func (dc *dohClient) newRequest(m *D.Msg) (*http.Request, error) {
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buf, err := m.Pack()
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if err != nil {
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return nil, err
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}
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req, err := http.NewRequest(http.MethodPost, dc.url, bytes.NewReader(buf))
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if err != nil {
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return req, err
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}
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req.Header.Set("content-type", dotMimeType)
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req.Header.Set("accept", dotMimeType)
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return req, nil
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}
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func (dc *dohClient) doRequest(req *http.Request) (msg *D.Msg, err error) {
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client := &http.Client{Transport: dc.transport}
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resp, err := client.Do(req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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buf, err := io.ReadAll(resp.Body)
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if err != nil {
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return nil, err
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}
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msg = &D.Msg{}
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err = msg.Unpack(buf)
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return msg, err
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}
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func newDoHClient(url, iface string, r *Resolver) *dohClient {
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return &dohClient{
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url: url,
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transport: &http.Transport{
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ForceAttemptHTTP2: true,
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DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
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host, port, err := net.SplitHostPort(addr)
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if err != nil {
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return nil, err
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}
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ip, err := resolver.ResolveIPWithResolver(host, r)
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if err != nil {
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return nil, err
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}
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options := []dialer.Option{}
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if iface != "" {
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options = append(options, dialer.WithInterface(iface))
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}
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return dialer.DialContext(ctx, "tcp", net.JoinHostPort(ip.String(), port), options...)
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},
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TLSClientConfig: &tls.Config{
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// alpn identifier, see https://tools.ietf.org/html/draft-hoffman-dprive-dns-tls-alpn-00#page-6
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NextProtos: []string{"dns"},
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},
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},
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}
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}
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